Vacuum cleaner

ABSTRACT

A vacuum cleaner includes an electric motor for driving a rotational brush for brushing dust particles from a surface to be cleaned, an electric blower for generating a suction air stream for sucking in the dust particles, a dust chamber for collecting the dust particles therein, a motor controller for controlling the electric motor, an input controller for controlling the electric blower, a current detector for detecting a current flowing through the motor controller, and a temperature detector for detecting a temperature of the electric motor. If the temperature of the electric motor increases over a predetermined temperature value, the electric motor is stopped and the stoppage of the electric motor is detected by the current detector.

FIELD OF THE INVENTION

The present invention relates to a vacuum cleaner; and, moreparticularly, to a control mechanism for an electric motor for driving arotational brush which brushes dust particles.

BACKGROUND OF THE INVENTION

Conventional vacuum cleaners in general are configured as illustrated inFIGS. 5 and 6.

As shown in the figures, vacuum cleaner main body 50 includes electricblower 51 for generating a suction air stream for sucking in dustparticles and dust chamber 52 for collecting dust particles therein,wherein dust chamber 52 is provided at a suction side of electric blower51, i.e., above electric blower 51. Hose 60 communicated at one endthereof with dust chamber 52 is installed at a frontal portion of vacuumcleaner main body 50, and the other end of hose 60 is connected tosuction head 80 including rotational brush 53, electric motor 81 fordriving the rotational brush 53, and so forth. Suction head 80, hose 60and dust chamber 52 form an air suction passage.

In general, a user controls operations of electric blower 51 andelectric motor 81 for rotating rotational brush 53 depending on thestate of a floor to be cleaned by manipulating switch 82 installed onhandle 54. Here, electric motor 81 is cooled down by the air stream thatis made to flow in the air suction passage by the operation of electricblower 51 (see, for example, specification of U.S. Pat. No. 6,533,611).

However, if the air stream is not generated sufficiently strongly in theair suction passage due to dust particles accumulated in dust chamber52, electric motor 81 cannot be adequately cooled down, and electricmotor 81 is heated up. As a solution to this problem, a temperaturesensor having a self-hold function is installed at a vicinity ofelectric motor 81 to prevent electric motor 81 from being abnormallyoverheated. Further, recently, there is proposed a vacuum cleaner havingan operational mode in which rotational brush 53 is operated at a lowrotational speed to prevent a scratch on the floor to be cleaned.

However, in accordance with the above-described configuration of theconventional vacuum cleaner, when electric motor 81 is operated in amode in which the rotational speed of electric motor 81 is low, therebylowering the torque of electric motor 81, electric motor 81 can beeasily locked. For the reason, the temperature sensor is installed nearelectric motor 81 to prevent it from being overheated.

However, a temperature sensor in general, especially the one with theself-hold function is of a high price.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide alow-cost vacuum cleaner having a high safety and an increased userconvenience.

In accordance with a preferred embodiment of the present invention,there is provided a vacuum cleaner including: an electric motor fordriving a rotational brush for brushing dust particles from a surface tobe cleaned; an electric blower for generating a suction air stream forsucking in the dust particles; a dust chamber for collecting the dustparticles therein; a motor controller for controlling the electricmotor; an input controller for controlling the electric blower; acurrent detector for detecting a current flowing through the motorcontroller; and a temperature detector for detecting a temperature ofthe electric motor, wherein if the temperature of the electric motorincreases over a predetermined temperature value, the electric motor isstopped and the stoppage of the electric motor is detected by thecurrent detector.

In accordance with another preferred embodiment of the presentinvention, there is provided a vacuum cleaner including: an electricmotor for driving a rotational brush for brushing dust particles from asurface to be cleaned; an electric blower for generating a suction airstream for sucking in the dust particles; a dust chamber for storing thedust particles therein; a motor controller for controlling the electricmotor; an input controller for controlling the electric blower; a motordetector for detecting whether the electric motor is being driven ornot; and a temperature detector for detecting a temperature of theelectric motor, wherein the electric motor is stopped unless outputsfrom the motor detector and the temperature detector are in.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodimentsgiven in conjunction with the accompanying drawings, in which:

FIG. 1 is a side view of a vacuum cleaner in accordance with a firstpreferred embodiment of the present invention;

FIG. 2 sets forth a circuit block diagram of the vacuum cleaner inaccordance with the first preferred embodiment;

FIGS. 3A and 3B provide partial cross sectional views of majorcomponents of a vacuum cleaner which stands upright in a standing stateand is being used in a cleaning state, respectively, in accordance witha second preferred embodiment of the present invention;

FIG. 4 presents a circuit block diagram of the vacuum cleaner inaccordance with the second preferred embodiment of the presentinvention;

FIG. 5 shows a perspective view of a frontal portion of a conventionalvacuum cleaner; and

FIG. 6 depicts a perspective view of a rear portion of the conventionalvacuum cleaner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. Here, it is to benoted that the present invention is not limited thereto.

First Preferred Embodiment

FIG. 1 is a side view of a vacuum cleaner in accordance with a firstpreferred embodiment of the present invention and FIG. 2 sets forth acircuit block diagram thereof.

Referring to FIGS. 1 and 2, the vacuum cleaner includes electric motor 1for driving rotational brush 2 for brushing dust particles on a floor tobe cleaned; electric blower 3 for generating suction air stream forsucking in dust particles; dust chamber 4 for collecting dust particlestherein; motor controller 5 for controlling the rotational speed ofelectric motor 1; input control unit 6 for controlling electric blower3; and current detector 7 for detecting an electric current flowingthrough motor controller 5.

Further, temperature detector 8 detects the temperature of electricmotor 1. In the first preferred embodiment, temperature detector 8includes cheap thermostat 9 (of a self-reset type) and is connected toelectric motor 1 in series. As for thermostat 9, if the temperature ofelectric motor 1 increases up to a first predetermined value (e.g., 120°C.), a closed contact point of thermostat 9 is opened, whereas theopened contact point is closed again if electric motor 1 is cooled downsuch that its temperature decreases to a second predetermined value(e.g., 70° C.). Further, switch 10 installed on a handle of the vacuumcleaner is used for a user to turn on or off the operation of the vacuumcleaner.

Below, operation of the vacuum cleaner having the above-describedconfiguration will be explained in detail.

If the temperature of electric motor 1 is low, the contact point ofthermostat 9 of temperature detector 8 is closed. As a result, powersupply to electric motor 1 is continued, and current detector 7 detectsthe amount of the current flowing through motor controller 5.

Here, if rotational brush 2 is operated at a low rotational speed for along period of time or if rotational brush 2 is locked due to a heavyload of the surface to be cleaned, such as a thick, heavy carpet orelectric motor 1 itself is locked, the temperature of electric motor 1increases. In this case, if the temperature of electric motor 1 isdetected to reach the first predetermined temperature value bytemperature detector 8, the contact point of thermostat 9 of temperaturedetector 8 is opened, and at the same time current detector 7 willdetect there is no current flowing through motor controller 5.

When it is determined that electric motor 1 has been stopped, motorcontroller 5 controls to have switch 10 to be turned off or outputs astop signal of electric motor 1 continuously until switch 10 is turnedoff or power supply is cut off. For example, if it is determined thatelectric motor 1 is stopped, the power is not supplied to electric motor1 until switch 10 is turned off or power supply is cut off.

By this mechanism, even in case the temperature of electric motor 1 isreduced down to the second predetermined value, electric motor 1 ismaintained stopped.

Further, though the first preferred embodiment has been described forthe case of detecting the current flowing through motor controller 5, itis also possible to detect a current flowing through electric motor 1 orto employ a rotational number detector, e.g., a revolution-counter, fordetecting a rotational status of electric motor 1. In addition, thoughswitch 10, which is a power switch for starting or cutting off a powersupply, is exemplified as an “off” switch for use in stopping the loadon electric motor 1 or electric blower 3 in the above-described firstpreferred embodiment, it is also preferable to use a signal switch (notshown) instead of the power switch to generate an “off” signal. In thiscase, by processing the “off” signal through a microprocessor, the loadcan be stopped. That is, the “off” switch can be implemented by anelement other than the power switch.

Second Preferred Embodiment

FIGS. 3A and 3B present partial cross sectional views of majorcomponents of a vacuum cleaner in accordance with a second preferredembodiment of the present invention. FIG. 4 is a circuit block diagramthereof. Here, parts identical to those described in the first preferredembodiment will be assigned same reference numerals, and descriptionthereof will be omitted.

Referring to FIGS. 3A to 4, electric motor detector 11 detects whetherelectric motor 1 is being driven or not. In the second preferredembodiment, employed as electric motor detector 11 is micro switch 12for distinguishing a state where rotational brush 2 is not driven, i.e.,a main body standing state (as shown in FIG. 3A) in which main body 15stands upright from a state where main body 15 is inclined to driverotational brush 2, i.e., a cleaning state (as shown in FIG. 3B).Reference numeral 12 a is a lever of micro switch 12.

When main body 15 is in the standing state, lever 12 a of micro switch12 is opened, as illustrated in FIG. 3A, so that a contact point ofmicro switch 12 is also in an open state. When the vacuum cleaner is inthe cleaning state, on the other hand, lever 12 a of micro switch 12 isclosed, as shown in FIG. 3B.

Furthermore, as illustrated in FIG. 4, temperature detector 8 includesthermostat 9 and first fixed resistor 13 (e.g., 1 kΩ) connected tothermostat 9 in parallel. Also, electric motor detector 11 is connectedto temperature detector 8 in series, which is also connected to secondfixed resistor 14 (which is set to have a value of 1 kΩ identical tothat of first fixed resistor 13) in series. In this configuration, avoltage divided by first and second resistor 13 and 14 can be inputtedto motor controller 5.

Hereinafter, operation of the vacuum cleaner configured as describedwill be explained.

When main body 15 is in the standing state, the contact point of microswitch 12 is in an open state. Therefore, 0V is inputted to motorcontroller 5 regardless of the current state of temperature detector 8.In case main body 15 is inclined in the cleaning state, however, thecontact point of micro switch 12 is in a closed state, and a voltage isinputted to motor controller 5 as follows.

If the temperature of electric motor 1 is low, the contact point ofthermostat 9 is closed, so that 5V is inputted to motor controller 5.

However, if the temperature of electric motor 1 is high, the contactpoint of thermostat 9 is opened, so that 2.5V is inputted to motorcontroller 5.

Accordingly, detection of a current state of the vacuum cleaner andcontrol operation are performed as follows based on an input voltage tomotor controller 5. If an input of 0.0V is detected, main body 15 isdetermined to be in the standing state, so that electric motor 1 isstopped; if an input of 2.5V is detected, main body 15 is determined tobe in the cleaning state, but since the temperature of electric motor 1is high, electric motor 1 is maintained stopped; and if an input of 5.0Vis detected, main body 15 is determined to be in the cleaning state andthe temperature of electric motor 1 is low, so that electric motor 1 isoperated.

Conventionally, determination of whether main body 15 is in a standingstate or in a cleaning state and whether the temperature of electricmotor 1 is high or low has been performed individually by dual systems.However, in accordance with the second preferred embodiment, byconnecting first fixed resistor 13 to thermostat 9 in parallel,detection of a standing or a cleaning state of main body 15 and a highor a low temperature of electric motor 1 can be carried out by a singlesystem at a low cost.

If it is found that electric motor 1 is stopped in the cleaning state, astop signal indicating the stoppage of electric motor 1 is continuouslyoutputted until an “off-operation” is inputted by switch 10 or powersupply is cut off. Thus, even in case the temperature of electric motor1 is reduced to, e.g., the second predetermined value, electric motor 1is maintained stopped without being driven to rotate unprepared.

Moreover, in the second preferred embodiment, though thermostat 9 andfirst fixed resistor 13 connected thereto in parallel are used astemperature detector 8, if a thermistor or the like is employed astemperature detector 8, installation of the fixed resistor becomesunnecessary and it is still possible to perform a delicate control ofthe temperature of electric motor 1 (for example, with regard to adetermination value for use in stopping a driving signal of electricmotor 1 when the temperature of electric motor 1 increases and adetermination value for allowing an output of the driving signal ofelectric motor 1 when the temperature of electric motor 1 decreases, thetwo values can be changed properly.

In particular, driving switch 20 for use in resuming the drivingoperation of electric motor 1 manually is provided as shown in FIG. 4.If the temperature of electric motor 1 is reduced down to or below thesecond predetermined temperature value after electric motor 1 is stoppedbecause its temperature increases up to or over the first predeterminedvalue, it is possible to resume an output of a driving signal ofelectric motor 1 from motor controller 5 by manipulating driving switch20. Thus, by using driving switch 20, unprepared rotation of electricmotor 1 can be prevented when the temperature of electric motor 1 isreduced, and, also, a normal cleaning operation can be resumed byoperating driving switch 20 at a point in time when the temperature ofelectric motor 1 falls below the second predetermined temperature value.

As described, the vacuum cleaner in accordance with the presentinvention has merits in that it can be fabricated at a low cost andthere is little limit in the number of wirings therein. Furthermore, itcan detect the stoppage of the electric motor accurately, thus providingimproved safety and user convenience. Therefore, the present inventionhas advantages when it is applied to various vacuum cleaners or dustcollectors for use in household and commercial environments. Inaddition, the rotational state of the electric motor can be detected ata low cost to secure a high level of safety readiness and it is possibleto securely control the rotation of the electric motor when, e.g., theelectric motor is abnormally overheated or the vacuum cleaner is not ina cleaning state. Moreover, it is possible to properly setting the stoptemperature and the drive temperature of the electric motor to preventthe electric motor from being overloaded.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the scope of the invention as defined in the following claims.

1. A vacuum cleaner comprising: an electric motor for driving arotational brush for brushing dust particles from a surface to becleaned; an electric blower for generating a suction air stream forsucking in the dust particles; a dust chamber for collecting the dustparticles therein; a motor controller for controlling the electricmotor; an input controller for controlling the electric blower; acurrent detector for detecting a current flowing through the motorcontroller; and a temperature detector for detecting a temperature ofthe electric motor, wherein if the temperature of the electric motorincreases over a predetermined temperature value, the electric motor isstopped and the stoppage of the electric motor is detected by thecurrent detector.
 2. The cleaner of claim 1, further comprising a switchfor turning on and off an operation of the vacuum cleaner, wherein oncethe stoppage of the electric motor is detected by the current detector,the stoppage of the electric motor is maintained until the operation ofthe vacuum cleaner is turned off by the switch or a power supply to thevacuum cleaner is cut off.
 3. A vacuum cleaner comprising: an electricmotor for driving a rotational brush for brushing dust particles from asurface to be cleaned; an electric blower for generating a suction airstream for sucking in the dust particles; a dust chamber for storing thedust particles therein; a motor controller for controlling the electricmotor; an input controller for controlling the electric blower; a motordetector for detecting whether the electric motor is being driven ornot; and a temperature detector for detecting a temperature of theelectric motor, wherein the electric motor is stopped unless outputsfrom the motor detector and the temperature detector are inpredetermined ranges.
 4. The cleaner of claim 3, wherein the motordetector and the temperature detector are connected in series.
 5. Thecleaner of claim 4, further comprising a switch for turning on and offan operation of the vacuum cleaner, wherein once the electric motor isstopped because the outputs from the motor detector and the temperaturedetector are not in the predetermined ranges, the stoppage of theelectric motor is maintained until the operation of the vacuum cleaneris turned off by using the switch or a power supply to the vacuumcleaner is cut off.
 6. The cleaner of claim 2, further comprising adriving switch for use in driving the electric motor manually, whereinif the temperature of the electric motor is reduced to or below a presettemperature value after the electric motor is stopped, the electricmotor can be reset to be controllable by the motor controller bymanipulating the driving switch.
 7. The cleaner of claim 5, furthercomprising a driving switch for use in driving the electric motormanually, wherein if the temperature of the electric motor is reduced toor below a preset temperature value after the electric motor is stopped,the electric motor can be reset to be controllable by the motorcontroller by manipulating the driving switch.
 8. The cleaner of claim6, wherein, as for a determination value for use in stopping a drivingsignal from the motor controller in case the temperature of the electricmotor increases and a determination value for use in allowing an outputof the driving signal from the motor controller in case the temperatureof the electric motor decreases, the two determination values are set tobe differently changeable.
 9. The cleaner of claim 7, wherein, as for adetermination value for use in stopping a driving signal from the motorcontroller in case the temperature of the electric motor increases and adetermination value for use in allowing an output of the driving signalfrom the motor controller in case the temperature of the electric motordecreases, the two determination values are set to be differentlychangeable.